Method and apparatus for cementing heels to shoes



Dec. 12, 1961 H. E. COOPER 111 3,012,260

METHOD AND APPARATUS FOR CEMENTING HEELS T0 SHOES Filed Feb. 25, 1959 4 Sheets-Sheet 1 Fl 6. l 'INVENTOR.

M a. fow, 1H3 BY zta fmvm ATTORNEYS Dec. 12, 1961 H. E. COOPER 1n 3,012,260

METHOD AND APPARATUS FOR CEMENTING HEELS TO SHOES Filed Feb. 25, 1959 4 Sheets-Sheet 2 lo o o o o 22 Z0 26 Z6 Z6 a INVENTOR.

M 5 fmu zz BY ATTORNEYS Dec. 12, 1961 H. E. COOPER In 3,012,260

METHOD AND APPARATUS FOR CEMENTING' HEELS T0 SHOES Filed Feb. 25, 1959 4 Sheets-Sheet s IN V EN TOR.

AT TOR N EYS Dec. 12, 1961 H. E. COOPER m 3,012,260

METHOD AND APPARATUS FOR CEMENTING HEELS T0 SHOES Filed Feb. 25, 1959 4 Sheets-Sheet 4 ATTOR N EYS United States Patent Ofice 3,012,260 Patented Dec. 12, 1961 chusetts Filed Feb. 25, 1959, Ser. No. 795,379 5 (Iiaims. (Cl. 1242) This invention relates to a method and apparatus for attaching heels to shoes, and more particularly to a method and apparatus for attaching heels to womens shoes by means of thermoplastic hot melt adhesive cements.

in the modern manufacture of womens conventional high heel shoes, as opposed to various sandals, slippers, novelty types, and the like, it is generally necessary to attach the heel to the shoe while the shoe is still on the wood last in order that the shoe may be properly finished. As a final step the wood last is removed and nails are driven from the inside through the insole into the heel, holding the heel firmly during the life of the shoe. It is the initial or preliminary attaching or heeling of the shoe with which we are herein concerned.

In general the problem of attaching heels to womens shoes is rendered complex by the shape of the heel itself which renders it dificult to find space for inserting attaching members. For many years the shoe industry has tried various ways for attaching womens shoe heels by means of combinations of glue, temporary screws and the like, but such method have had serious drawbacks. When emulsion or solvent type glues have been employed, special C-clamps were needed to maintain the pressure during drying, or otherwise screws were inserted to hold the parts together during drying. In either case the process was inefficient. On the other hand, while thermoplastic cements (as adhesives based on synthetic resins and applied as molten semi-liquids as often called in the shoe industry) do not take long to harden, they have not been used generally for attaching womens shoe heels. The difliculty in using thermoplastic cement of adequate strength is principally that it hardens too fast and once hardened it is extremely difiicult to remove. Thus, with thermoplastic cement, the operator must place the heel on the shoe and position it accurately within a very few seconds or else the heel will be fixed to the shoe in a position of misalignment. Secondly, the operator must make sure that he has an accurate amount of cement in place between the heel and the shoe or else one of two things may happen. If he does not have enough cement, a good bond will not be created; and if he has too much cement, then an overflow may permanently blemish the upper rendering the shoe unsuitable for sale at the price intended.

It is, therefore, a primary object of my invention to provide a method and apparatus for attaching heels to womens shoes employing thermoplastic cement in such a way as to form a good bond but without danger of overflowing cement on the upper of the shoe, and with such an arrangement that the operator may attach the heel without requiring special C-clamp or screw pressure members, a long waiting period, or any period of inactivity for the operator.

It is a further object of my invention to provide a machine which will utilize th advantages of fast setting, strong bonding, thermoplastic adhesives and yet which will itself automatically compensate for most irregularities in shoe heel size and placement.

It is an additional object of my invention to provide a shoe heel attaching machine so constructed that the shoe last, once in place on the machine, need not be moved during the subsequent heel fitting, bonding and pressing operations.

It is yet a further object of my invention to provide a machine for heeling womens shoes wherein pressure to hold the heel in place is applied to the base of the heel.

It is still a further object of my invention to provide a womens shoe heeling machine in which the amount of cement to be applied between heels and shoes may be predetermined and this amount controlled automatically.

It is yet an additional object of my invention to provide a womens shoe heeling machine having a pressure applying means moving vertically only.

It is another object of my invention to provide a machine in which the pressure applied to the heel while the cement is setting can be predetermined and automatically regulated despite difierences in heel size.

It is a further object of my invention to provide forkshaped elements for applying pressure to heels mounted on a row of shoe lasts and by means of which pressure can be partially applied to any one heel without removing pressure from any other heel.

In the accomplishment of these and other objects of my invention in a preferred embodiment thereof, I employ a frame supporting a table and having adjustably mounted thereon three shoe last supports. Somewhat above each last support a fork-shaped pressure applying element is mounted for vertical sliding motion in response to pneumatic mechanism located below the table. The pressure fork elements are pivotally mounted to swing freely in a horizontal plane in order to adjust to diiferent sizes and shapes of heels as they apply pressure. In operation, a shoe last is placed on a last support, a heel with adhesive appropriately applied is placed in position on the shoe and the fork element is then brought down against it. As the fork descends over the increasingly broad stem of the heel, the pivotal mounting of the fork permits it to adjust itself so that the two tines of the fork press evenly against the broad base portion of the heel. This arrangement of parts thus automatically compensates for irregularities in shoe heel size and position. In addition, this arrangement permits pressure to be applied predominantly to the base and around the periphery thereof rather than, as in the prior art, to the lift end of the heel. Consequently, the heel cup is held firmly in place against the heel seat and the periphery is held tight thereby minimizing the possibility of seepage outwardly over the upper.

A further feature of my invention is the verticallyascending and descending pressure fork elements. The employment of pneumatic pressure to actuate the fork elements of my invention constitutes an additional feature of my invention for it makes possible the use of any size heel on any size shoe of the same general type or style without compensating adjustments of fork heights and last support positions. The fork descends each time until heel resistance is equal to the force developed by the air pressure in the system, at which point the fork remains until air pressure is released. This is true no matter at what point in its descent fork meets heel and comes to rest.

Adjacent the pressure forks and, in my preferred embodiment, directly above them is an arrangement for storing, melting, metering and dispensing adhesive. This arrangement permits applying a predetermined amount of adhesive to the heel and thereby contributes to that feature of my invention which insures that the same amount of adhesive will be dispensed to each'shoe and heel. In this connection still another feature of my invention has to do with the relationship between the setting time of the cement and the provision of a precise metering mechanism for the cement. In the preferred embodiment, the setting time for the cement is approxhandling time for each last;

imately 10 seconds. However, the time required for the operator to remove a heeled last, place a fresh last on the last support, take a new heel, deposit the cement on the heel, place the heel on the shoe and apply the bonding pressure theretois about five seconds. Thus, while one heel is being pressed, the operator has time to servicetwo other stations. In this way the cement metering feature of my invention is linked to the operation of the process and makes it possible for me to use as few as three last supports without causing the operator to waste time waiting for the cement to harden or otherwise to expend needless efiort while at the same time obtaining maximum pro duction. The formula for determining the optimum number of stations is X rhl where X is the setting time for the cement and Y is the A'further feature of my invention relates to the'means I employ for actuating the pressure forks. With my in vention these forks are actuated by means of a foot pedal which, when only partially depressed, will actuate a given fork, but if the pedal is released before being fully depressed, it will permit that same fork to lift. This gives the operator an opportunity to re-position the heel or make other adjustments as may be needed before the vce ment has set. With this arrangement, fully depressing the foot pedal then causes that pressure fork to, lock in posi; tion under pneumatic pressure and simultaneously releases the pressure in the next succeeding pressure fork.

V In regard to, the pressureforks of my invention, there is a particular relationship to the use of thermoplastic cement which is not readily apparent, but which nevertheless I wish to make very clear herein and to'claim. Since thefpressure forks are pivotally mounted in order to .ac-. V

commodate various heel sizes and shapes, and both rights and kits, and since the surface level of the last thus varies slightly to one side or the other, a complete elimination of slight lateral forces tending to move the heel out of accurate position is impossible. The knowledge that such forces could not be totally eliminated has actually been a major' obstacle in this field hitherto and has led previous machine manufacturers to build numerouscumbersome controls and adjustment mechanisms into their equipments to accommodate changes in size and shape. I have found, on the other hand, that my swivel-mounted pressure forks are ideal when quick setting cements are employed because the cement very rapidly (within three seconds) becomes highly viscous at the periphery and holds the heel against any harmful lateral sliding. Also by covering my pressure forks with rubber, they grip the 'heel and hold the same against relative motion. 7 This latter feature does not eliminate all possible sliding forces, but'itdoes eliminate twisting and sliding longitudinally relative to the forks. V I

' Another feature of significance relates to the ability of the thermosetting cementlto sealits elf off in a constricted. V

passage. 1 In practice, find it important to apply a slight excessof cement to the heel. When this is done, and the heel is then placed under pressure against the shoe, the

' cement at first starts moving outwardly toward the heel periphery. However,-when the cement approaches the peripheral margin ofthe heel, it reachesa'constricted area where the adjacent portions of the heel and shoe rapidly V absorb the heat inthece ment, and the cement being less iri'vol'ume has less heat to lose. In .this way the cement viscosity increases sharplytoward themargins and thereby. effectively prevents .further passage of cement out I wardly toward the. upper. In some instances, a slightly larger. gap existsbetween the'heel and outsole toward the forward. edge of the heel, but leakage in such area is not. as harmful as next to the upper, and moreover evenin bination of thermoplastic cements and plastic heels. Plastic heels have hitherto been extremely difficult to attach, but with my invention cements maybe employed which are compatible with the plastics from which heels are molded; in fact, in some cases, the'cements virtually comblue with the heel materials under heat and pressure.

Further objects and features of my invention will best be understood and appreciated from a detailed description of a preferred embodiment thereof, selected for purposes of illustration, and shown in the accompanying drawings, in which:

. FIG. 1 is a view in front elevation ofthe general arrangement of the heel attaching apparatus of my invention;'v V V v FIG. 2 is a view in perspective in front elevation showing the apparatus in operation;

FIG. 3 is a fragmentary view showing the valve actuating mechanism;

FIGS. 4 and 5 are views further demonstrating the cam action of the mechanism illustrated in FIG. 3;

FIG. 6 is a view in partial cross section of the cement metering device employed in my invention; 7 FIG. 7 is a view in perspective of a pressure fork employed in holding a heel in place and under pressure;

and a FIG. 8 is a view incross section of a variation of the apparatus of my invention. r

".The preferred embodiment of my invention herein shown includes in its'general organization a base frame including vertical end members 10, intermediate cross bars 12 and a platform or table top 14. Spaced across the top of the table '14, I provide three upstanding last supports 16. Thelast supports 16 are cylindrical memhers adapted to engage the conventional last supporting hole in the heel. area of the last. The last supports 16 are mounted on laterally and longitudinally adjustable blocks 18 which may be placed in a desired position andthen clamped by means of screw clamps 26.

In FIG. 2 a last will be seen mounted on the left hand last support 16 with aheel in place thereon. In this position. pressure is applied to the heel by means of a pressure fork 22 which is pivotally connected to a cross head 24, which is in turn mounted for vertical motion on a shaft 26. Itwill be understood that each last support 16 has its corresponding pressure fork ZZ-and associated ele merits.

fork 22, the said fork 22 descends until it contacts the heel and presses the same against the last. In this way it makes no difference whether the shoe is large or small because the pressure applied to the heel corresponds to the pneumatic pressure in the ram 28 regardlessof the height 0 at whichthepressure fork cOntactsthe heel.

- In orderto accommodate varying sizes and shapes of heels,'as well as shoe rights and lefts, the pressure forks 22 are pivotally connected to the cross heads 24 by vertically disposed pivots 30. In this way the pressure forks 22 are free to pivot in a horizontal plane but transmit the full vertical thrust of the shaft 26 to the heel. Since the heels are not always level, there is usually a slight lateral vectorwhichwould render thi's'type of pressure mechanism,entirely unsatisfactory unless quick setting cements 7O arejemployed. .In thepreferr'ed embodiment, I employ thermoplastic polymeric vinyl compounds in molten condi- I tion at aboutBOO F., which become semi-solids at about 200 f.F.,' and become firm below. 140 F. In use they hecomeset within about ,ten seconds after application,

Thus, the slight lateral forces do not 'have time tocause any noticeable shifting. In addition to the foregoing, shifting forces are also minimized by providing the pressure forks 22 with rubber friction covers 23. These covers hold the heel against slipping longitudinally or twisting relative to the fork. They do not completely eliminate all lateral forces, but they serve to limit the path of possible motion to an arc about the pivot 30.

The pneumatic rams 28 are double acting rams. Each is controlled by a valve 32, which is in turn controlled by a cam 34 acting through a rocker arm 36 carrying a cam follower 37. The cams 34 are mounted on a shaft 38 which is driven intermittently in rotation by a foot pedal 49 arranged to advance the shaft 38 through degrees of arc for each stroke of the pedal 40. The intermittent motion is facilitated by means arranged to drive shaft 38 when pedal 49 is depressed. The cam followers 37 seat into essentially semi-cylindrical notches 36 in the periphery of each cam 34 at 60 degree intervals. Thus each valve 32 is actuated by its respective cam 34 on every third stroke of pedal 40, and the earns 34 are arranged to do this in sequence. The valves 32 and rams 28 are constructed so that when each cam follower 37 is set in the notch 46 of its respective cam 34, the ram 28 is actuated to draw the shaft 26 and pressure fork 22 upwardly. Conversely, when cam followers 37 are elevated out of notches 46, the valves 32 reverse the pneumatic flow and return the rams 23 to the down position.

In connection with the cam followers 37, however, it should be specifically noted that the valves 32 are adjusted to actuate the rams 28 as soon as the cam followers 37 start rising out of the notches 46. In this way, a valve 32 may be tentatively actuated causing the appropriate pressure fork 22 to descend, but without fully lifting the cam follower 37 out of its notch 46. In this way the operator can apply a tentative pressure to the heel and check the heel for accurate positioning. If the heel needs to be repositioned, the operator can then let up on the pedal 40, the cam follower 37 will drop back into the notch 46 in which it has just been, and the associated valve 32 will then close causing the pressure fork to rise. Once the heel is repositioned accurately, the operator can fully depress the pedal 40 causing the cam follower 37 to come completely out of the notch 46 and take its pos tion on the high surface of the cam 34 as may be seen in FIGS. 4 and 5.

In order to deposit a metered and accurate amount of cement in the cup of the heel, I provide a heel metering device illustrated generally in cross section in FIG. 6. This device includes a container 48 containing the thermoplastic cement which is kept in a molten condition by means of a heater 49 attached to underside of the tank, controlled by a thermostat 50. In the lower front portion of the container 48, I provide a small metering chamber 52 where the cement about to be deposited is held immediately prior to ejection. A metered ejection of the molten cement from the chamber 52 is effected by a pair of pneumatic rams 54 and 56 mounted on top of the container 48, and actuated simultaneously by a valve 72 which is opened by a hand lever 74. When cement is desired, a heel is placed below an ejection orifice 60 and the hand lever 74 is raised. This actuates rams 54 and 56 simultaneously. The ram'54 lifts a piston 58 and thereby opens ejection orifice 60 at the bottom end of the metering chamber 52. At the same time as the ram 54 is opening the orifice 60, the ram 56 drives a plunger 62 into the metering chamber 52. As plunger 62 enters the metering chamber 52, a ball check valve 64 closes an orifice 66 in the upper wall of the metering chamber 52 and by preventing the upward passage of molten cement causes a metered ejection of molten cement through orifice 69. Cement flow then ceases, the operator releases hand lever 74 and the rams 54 and 56 return to their former positions with piston 58 again blocking oif orifice 69, and plunger 62 rising upwardly in response to upward forces of a spring 70. As plunger 62 so rises,

ball check valve 64 opens orifice 66 and a fresh supply of molten cement enters chamber 52. The stroke of plunger 62, and hence the quantity of cement to be metered, is regulated by a threaded stop element 68 which stops the upward motion of plunger 62 and thereby determines the starting position it will assume during the metering stroke.

From the foregoing description it will now be seen that the operation of my invention involves placing a shoe with its last on a last support, metering a quantity of molten thermoplastic cement into the concave cup area of a heel, placing the heel in position on the last, partially depressing the foot pedal 40 to cause the pressure fork associated with that particular last support down onto the heel. Having observed that the heel is in proper position, the foot pedal 40 is then fully depressed at which time one of the other pressure forks 22 will rise. When this happens, the last which hasbeen under pressure from the fork which just rose will be removed from the last support and placed in a rack. A new shoe will be brought from the rack and placed on the last support, a new heel cemented and applied thereto, and brought under pressure of the pressure fork 22 as was described. This sequence of operation continues thereafter in rotation.

Numerous variations of this preferred embodiment of my invention will now be apparent to those skilled in the art. One such variation is shown in FIG. 8 and comprises a heated tube brought upwardly through the center of the last support 16, through the last, through the insole into a spot directly within the cup of the heel. By such an arrangement the heel may be placed in position on the last and held thereon by means of forks 22 prior to application of the molten cement. Once the heel is thus held, the molten cement may be injected into the area between the heel and the shoe with the apparatus shown in FIG. 8. Since further modifications will be apparent to those skilled in the art, it is not my intention to confine the invention to the precise form herein shown, but rather to limit the invention in accordance with the appended claims.

Having thus described and disclosed preferred embodiments of my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for cementing heels to shoes including a last support, means for applying pressure to a heel in position on a shoe on a last on said support, said pressure applying means comprising, a pneumatic ram and a pressure fork operatively associated therewith arranged to bring pressure to bear on said heel in vertical alignment with said last, and said pressure fork being pivotally mounted to swing freely in a horizontal plane with respect to said last whereby said pressure applying means accommodates right and left heels of varying sizes and designs without adjustment.

2. A method of cementing heels to shoes comprising: heating a thermoplastic cement to a molten state, metering a desired quantity of said cement and depositing same on the attaching surface of a heel, placing said heel on a shoe on a last, subjecting said heel to pressure in vertical alignment with said last without restriction against lateral sliding other than said pressure in vertical alignment, and rapidly hardening under said pressure said cement between said heel and said shoe before any substantial lateral sliding results from departures of the heel portion of the shoe from the horizontal with respect to said last.

3. Apparatus for cementing heels to shoes wherein a last support is employed in combination with pressure applying means arranged so that a shoe on a last may be placed on said last support, thermoplastic cement may be applied to a heel, the heel then placed on and pressed against said shoe, said apparatus having in combination: a swivel-mounted two-tined pressure fork positioned above and mounted for motion in vertical alignment with saidlast over the heel area thereof and for free hori zontlal pivoting motion, means for lowering said fork against .a heel on said last, and means onthe tines of said fork for gripping said heel-and holding the same against turning or sliding motion relative to said fork.

4. Heel cementing apparatus having in combination:

pressure forks for applying pressure toheels being cemented to shoes, pneumatic means for actuating said forks in a direction in vertical alignment with said shoe, -a .pivotal mounting for each said fork arranged to permitsaid forks freepivotal motion in, a horizontal plane relative. to saidshoe, and a friction surface on each said fork. for preventing relative motion between a heel and a said fork while under said pressure. 5., Heel cementing apparatus having in combination: a plurality .ofprcssure forks for applying pressure to heelsbeing cemented to shoes; pneumatic means for actuating each said fork in a direction in vertical alig'm ment with said shoes; and control mechanisms for said pneumatic means comprising, a valve for each pneumatic mechanism,-a cam and valve actuating cam follower for each said valve, a single cam shaft for said. cams, means for turning saidv shaftintermittently a predetermined number of degrees, said cams being adaptedto open said valves one at a time andin sequence,- wtihone said valve being opened for each said turn of said shaft; said earns,

cam followers and camshaft turning means further constructed and arrangedto open a given valve when said shaft is turned only a minor part of said predetermined number of degrees and to reclose the same and return to the former condition unless said shaft is turned a major part of said predetermined number of degrees; whereby said pressure, may be applied tentatively to a heel and without releasing the pressure on another heel beingpressed.

References Cited in the file of this patent UNITED STATES PATENTS sun- 

